Perfume is an important component of modern fabric softeners, particularly those delivered through the rinse cycle of a washing machine and those present in dryer sheets and other forms. It is estimated that the cost of perfume may represent about 50% of the overall formula cost of a typical rinse cycle fabric softener. However, there is often a high volume of wasted perfume in the laundry process; instrumental measurements have indicated that about 50 to 70% of the perfume ingredients in a commercial liquid fabric softener typically remain in the washing liquor, and thus are never deposited on the fabrics being treated.
Consequently, increasing perfume deposition efficiency onto fabrics is desirable because it may allow for a significant decrease in waste and cost of a commercial fabric softening product. Furthermore, by improving the deposition efficiency of the volatile ingredients in a perfume, new perfume notes can be introduced into fabric softening compositions and more effectively deposited onto treated fabrics.
In laundry products such as fabric softeners, the presence of a perfume is intended to make the compositions more aesthetically pleasing to consumers. Apart from the point of purchase perception, the perfume additives may impart a pleasant and longer lasting fragrance to fabrics that are treated therewith. However, as noted above, with regard to liquid fabric softening compositions that are added during the laundry process, the major portion of the perfume is often lost in the wash solution during the wash and therefore wasted.
Attempts have been made in the art to increase the efficiency and deposition of perfumes on fabrics. For example, the use of cross-linked cationic vinyl polymers has been discussed and explored in conjunction with fabric conditioning formulations and personal care compositions as a thickening agent, for example in International Patent Publication No. WO 90/12862 and U.S. Pat. No. 4,806,345. Various methods for achieving controlled active release have been developed. One of the simplest of such embodiments is described in Canadian Patent No. 1,111,616 to Young, and U.S. Pat. No. 6,042,792 to Shefer et al., which describe incorporation of perfumes into wax. U.S. Pat. No. 4,464,271 describes encapsulation technology for entrapping softener compositions and fragrance oils in solid particles. An example of such microencapsulation technology is embodied in capsules with perfume, which are broken under friction to provide an instant “burst” of fragrance when the capsules are ruptured.
These types of capsules may behave differently depending on the compositions with which they are used. In particular, they may be disadvantageous in that they can often leak in aqueous compositions containing high levels of surfactants and lower alcohols. As it is desirable to provide perfumed articles that are stable in fluid compositions but still liberate perfume during use, different approaches have been used; for example, building a coating around the particles as described in U.S. Pat. No. 5,137,646, or encapsulating perfume materials together with high C log P solvents to enable the fragrances to remain in the capsules for extended times without leaching from the capsules, as described in European Patent Publication No. 1 533 364 A3. However, there is an ongoing need for the improvement of perfume efficiency and deposition on fabrics and the capture of the more volatile ingredients of a perfume for fabric deposition.
The present invention is directed, in certain embodiments, to a cross-linked polymeric material designed as a perfume “sponge” to retain volatile perfume ingredients. In certain embodiments, the invention is directed to a polymeric material capable of increasing the efficiency of perfume deposition on fabrics such as cotton when used in conjunction with a rinse cycle fabric softening composition.